APT Renovation – Design & Build can take care of all aspects of a bespoke basement conversions in London from the design, excavation of core base, groundworks, waterproofing, tanking, understructure construction to fit outs and renovation of existing cellars and basements. Our own construction team will undertake the whole fit-out phase of the basement conversion project. The major benefit of our service is that you can work with a single team of groundwork specialists under one roof.

Over past years we managed to transform exceptional basement substructures. We combined client ideas and our expertise in constructing bespoke ground rooms and cellars. Our in-house team of architectural designers and understructure engineers who can create and transform any space you may desire.

We are also able to work on larger projects like “mega basements” and “super substructures” as well as large entertainment rooms, home cinemas, gyms, interactive children’s playroom, a study room, swimming pools and ground room spa spaces.


 Why Choose us for your Basement Conversion

Our in house team of qualified architectural designers and fine builders are capable to undertake any project small to large.

Our first step towards building your project will be to arrange free site visit at your property. We will discuss your basement and cellar conversion requirements and your ideas with you to form a design brief. This brief becomes our main objective. Using our extensive knowledge and experience we will advise you where the design will need to be tweaked to get the most out of your proposal and we will strive to exceed your expectations.

After the initial design approved by you, if required APT Renovation can take care of all the necessary plans etc, we will submit the basement and cellar designs for a planning application, party walls when required and the building control application.

We will act as an agent on behalf of you so, for the most part, all you need to worry about is paying the fees and waiting for the decision. We ensure that the designs that go in for the planning application have had the construction thought out and can be built without fundamental modification to the design.

Who we are

Our Design & Build services tailor-made to your personal needs, projects delivered and managed by team of:

• Project managers

• Architectural Designers

• Design consultants

• Quantity Surveyors

• Structural Engineers

• Professional Builders.

We take care of everything

APT Renovation offer full-service design and build services:

• Architectural Drawings

• Planning applications

• Building Control

• Project cost estimation

• Detailed architectural CAD / 3D designs

• Construction

APT Renovation team are always happy to hear your thoughts about your project, either on the phone or in person.

If you’d like to know more please arrange a FREE no obligation site meeting you.

Call Us: 0207 223 6417

Email Us: info@aptrenovation.co.uk



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we can help to transform your basement space


mega basement design and build service

APT Renovation is a basement specialist in London that has extensive experience and is able to deliver basement conversion requirements on time, budget and meet your expectations.


Free a No Obligation Site Visit / Consultation

APT Renovation will arrange site visit you at your property to discuss what would you like to create within your new or existing basement / cellar. We are happy to answer all essential questions you may have during our initial visit.
APT Renovation can offer a full service which includes submitting plans right through to the very last detail, or we are happy to just create your excavate and build your basement project from your already gained plans.
APT Renovation will ensure to send you a quotation within 8 days.

basement conversion company design service

Design Service

If you require a Planning and Design service for your basement conversion project, our in-house Architectural Designers, substructure and groundwork Structural Engineer, and Party Wall Surveyor are at hand to help you visualise your plans and go through them with you until you are completely happy with the final ideas. Our primary concern is to make our clients happy, so every process will be explained to you from beginning to end.

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Health and Safety at every stage

Health and Safety is of the utmost importance on every site that we work on, as it not only concerns all of our staff members, but everyone else in the vicinity; including you, your neighbours and even passers-by. Due to the nature of our work, there is always the risk of injury or even death, as ladders, tools and various other materials can be hazardous. Basement conversions in particular are technically very challenging, and can pose a number of different risks, with a large proportion of these projects in London regularly failing safety checks. Unguarded excavations and unprotected floor openings represent serious dangers to all those concerned. That is why our staff are expertly trained and will always diligently adhere to all necessary Health and Safety procedures and issues.

basement conversion british standard

British Standard 8102:2009

British Standard 8102:2009 is the ‘Code of practice for protection of below ground structures, substructures, understructure against water from the ground’. In essence, it is the primary design guide for structural waterproofing and groundworks in the UK, with the recent update being released in November 2009. If you are producing a waterproofing design, or you have advisors that are designing on your behalf, this document should cover every consideration possible. If you have further questions in regards to the BS8102, please feel free to contact us.

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An intuitive basement construction process will ensure your project will run smoothly and is monitored and overseen by managing director, Andi Pepaj, and managed by our project managers on site.

APT Renovation has over 17 years experience in underpinning and basement excavation adhering to basement standards to a very high-level finish.

You will be advised by your Project Manager who will be on site all day, every day and will be your first point of contact.

basement conversion tanking and excavation

Basement Tanking

Tanking, or ‘Type A barrier protection’ (BS8102 definition), is a specific form of waterproofing of underground rooms and understructures, although it is a common term applied to all forms of waterproofing. In the true sense of the word, tanking means blocking water out of a structure by employing a barrier product which is installed internally, sandwiched within, or applied externally to a structure. Tanking is still widely used and applied in building industry, but has declined in popularity in recent years where retrofit protection is required for existing basements.

basement conversion waterproofing


Waterproofing is a very important aspect in a basement and cellar conversion, particularly as the UK experiences a very high level of rainfall each year. A lack of waterproofing will eventually result in damp on walls, which not only looks bad, poor odours can be detrimental to your hygiene as well, and can cause significant damage to the paint job, the plastering and the finish. Worse still, damp can also lead to breathing problems and other health issues, so it is something that should be eradicated immediately.

APT Renovation Design & Build has had huge success over the years in waterproofing with Delta Membrane Systems and pumps. For basement waterproofing, the Delta sealed system ensures that all membranes are expertly sealed and secured, as well as any protrusions or crevices. Delta Systems are incredibly effective in dealing with adverse water conditions and especially basements that have the propensity to flood. There is a 30-year guarantee on all Delta membrane systems

Visit the Delta website

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Our construction team will be ready to make the underground rooms or space in your basement that you have been dreaming of, come to life. Our dedicated and experienced tradesmen will work tirelessly to complete your project on time with no stone being left unturned. Our aim is for you to be completely happy with the work, and we will only sign off the project once you have deemed it necessary to.

loft conversion insurance cover policy

Insurance and Guarantees

APT Renovation hold public liability insurance, and an all risks cover. This will cover you and our builders. APT Renovation Ltd offer a 15 year warranty on all structural work.

With hundreds of basement and cellar extension projects completed to date, APT Renovation has an outstanding reputation for being basement conversion specialists, dedicated to creating state of the art spaces, with immaculate attention to detail.


A Building Inspector will visit at regular stages throughout the project, their job is to make sure that we are adhering to all the latest substructure and groundwork building regulations. Upon completion of works The Building Inspector will make a final visit and you will be issued with a completion certificate.

Upon final completion you project you will receive following documentation where applicable:

Gas Safety Certificate, Electrical Sign Off Certificate, Drainage Layout, Plans as Built Drawings, Manufacturers Instructions For Appliances, Manufacturers Guarantees For Appliances, 10 Year Structural Guarantee